#
# @lc app=leetcode.cn id=96 lang=python
#
# [96] 不同的二叉搜索树
#

# @lc code=start
class Solution(object):
    def numTrees(self, n):
        """
        :type n: int
        :rtype: int
        """
        # dp[i]:节点为i时的树个数
        dp = [0]*(n+1)
        dp[0] = 1
        dp[1] = 1
        for i in range(2, n+1):
            for j in range(1, i+1): 
                dp[i] +=  dp[j-1]*dp[i-j]
        return dp[n]
        
# @lc code=end

